Absorbent core having swelling chamber

ABSTRACT

An absorbent article includes a liquid permeable topsheet, a liquid impermeable backsheet, an absorbent core being disposed between the topsheet and the backsheet, wherein the absorbent core include san absorbent material disposed in an absorbent deposition area and enclosed in a core wrap. The core further includes a swelling chamber disposed in between two external zones. The absorbent material comprises superabsorbent polymer. One or more permanent seals separate the chamber from each of the two external zones. The swelling chamber consists of absorbent material immobilized by water-responsive bonds, wherein said water-responsive bonds deteriorate upon exposure to water such that the absorbent material is flowable in the wet state; and the two external zones comprise absorbent material that is immobilized by thermoplastic adhesive, such that the absorbent material is immobilized in the wet state.

FIELD OF THE INVENTION

The disclosure relates to absorbent cores containing superabsorbentpolymers (SAP) for use in wearable absorbent hygiene articles thatabsorb and contain body exudates of the wearer, the cores having afunnel-shaped swelling chamber that influences the movement of the SAPafter wetting.

BACKGROUND OF THE INVENTION

Wearable absorbent hygiene articles typically include absorbent coresthat absorb and contain body exudates, e.g. urine or menstrual blood, ofthe wearer. The core absorbs and retains the exudate until a new articlemay be applied to the wearer. The core may contain SAP,cellulose-containing fibers, or both. Typically, the use of relativelymore fiber versus SAP results in a thicker core, and the use ofrelatively more SAP versus fiber results in a thinner core.

Where significant amounts of SAP are used, a phenomenon known asgel-blocking may occur after liquid insult. Gel-blocking refers to asituation where SAP particles deform during swelling and block theinterstitial spaces between the particles, or between the particles andfibers (if present), thus inhibiting the flow of liquid through theinterstitial spaces. Another concern that may occur where significantamounts of SAP are used is known as sagging. This refers to a situationwhere SAP absorbs and retains an amount of liquid weighing many timesits own weight, and this increased weight in the absorbent core ispulled by gravity, e.g. when the wearer is crawling or standing, andcauses a bunching up of material in the crotch area of the absorbentarticle. Due to the weight of the bunched up material, the absorbentarticle sags and may even pull away from the wearer. Yet another concernis that the crotch area may become very bulky after wetting. As SAP isoften placed at or near the point of urination in order to quicklyabsorb gushes of urine, and such areas tend to be in the medial andfrontal areas of the crotch, once these areas are wetted, they tend tobulk up, due to the SAP swelling as it absorbs and retains liquid.

U.S. Pat. No. 6,610,900 (Tanzer) discloses an absorbent article having aselectively stretchable absorbent composite between a topsheet and abacksheet, the absorbent composite having a selectively stretchablesubstrate layer and a plurality of pockets in or on the substrate layer.The pockets each contain a quantity of superabsorbent material, whichcan swell when exposed to liquid insult. When the substrate isstretched, the pockets become spaced further apart, alleviating gelblocking caused by adjacent pockets swelling toward each other. Thisinvolves discrete pockets containing SAP, but they are sealed andalthough the pockets can swell and stretch after wetting, they do notallow for post-wetting movement of SAP outside of the pocket.

US 2015/0174857A1 (Schmitz) discloses free flowing materials sandwichedbetween web materials, the web materials being bonded to each other atbonding points, which define bonding regions which delimit theaccumulation regions in which the free flowing material is positioned.This involves discrete pockets, where permanently bonded pocketcomprises two smaller compartments divided by a non-permanent bond—onecompartment containing SAP, the other empty. Upon wetting, thenon-permanent bond is broken and the SAP can occupy the previously emptycompartment.

The inventors have found that it is advantageous to move wetted SAPthrough the use of a funnel-shaped chamber from its original (dry)position in the core. The inventors have found that it is desirable tomove SAP in a one-way (unidirectional) manner, away from the crotch, butnot in the opposite direction, towards the crotch, and that it isdesirable to provide a core with a geometry that helps achieve this,particularly in the context of cores containing significant amounts ofSAP, perhaps even being free or substantially free of cellulosicmaterial. Further, we have found that it is desirable to provide a corethat enables one-way movement of wetted gel by at least a certaindistance, yet it provides good dry immobilization of the SAP prior toliquid insult, thus, inhibiting dry SAP from moving around within thecore, so it is at the proper place to receive liquid insult, but oncewetted, the wetted SAP moves away from the center of the crotch so thatit does not build up and create sagging, and/or reduces gel blocking.Without being bound by theory, it is believed that the cores of thepresent invention solve one or more of the aforementioned problems.

SUMMARY OF THE INVENTION

Disclosed are absorbent cores comprising absorbent material enclosed ina core wrap which comprises a liquid permeable substrate layer. Theabsorbent material comprises superabsorbent polymer. The core furtherincludes a swelling chamber disposed in between two external zones. Oneor more permanent seals separate the chamber from each of the twoexternal zones. In aspects, the swelling chamber consists of absorbentmaterial immobilized by water-responsive bonds, wherein saidwater-responsive bonds deteriorate upon exposure to water such that theabsorbent material is flowable in the wet state; and the two externalzones comprise absorbent material that is immobilized by thermoplasticadhesive, such that the absorbent material is immobilized in the wetstate. In further aspects, absorbent material is present in the externalzones and the swelling chamber and in the external zones absorbentmaterial flows differently than within the swelling chamber. In stillfurther aspects, the swelling chamber consists of absorbent materialimmobilized by water-responsive bonds, wherein said water-responsivebonds deteriorate upon exposure to water such that the absorbentmaterial is flowable in the wet state; and the two external zones arevoid of superabsorbent polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an exemplary absorbent core.

FIG. 2 is a cross sectional view of the absorbent core shown in FIG. 1taken perpendicular to the longitudinal axis at the crotch point, C′.

FIG. 3 is a partial plan view of a portion of an exemplary absorbentcore layer.

FIG. 4 is a partial cross sectional view of an exemplary absorbent core.

FIG. 5 is a plan view of an exemplary absorbent article.

FIGS. 6-6M illustrate exemplary absorbent cores having funnel-shapedchambers as described herein.

FIG. 7 is an example package comprising a plurality of absorbentarticles.

FIG. 8 is a sampling apparatus suitable for use in the BB test methoddescribed herein.

FIG. 9 is a tensile tester suitable for use in the BB test methoddescribed herein.

DETAILED DESCRIPTION OF THE INVENTION Definitions

The following term explanations may be useful in understanding thepresent disclosure.

As used herein, “absorbent articles” and “absorbent articles forpersonal hygiene” refer to disposable devices such as baby diapers,infant training pants, adult incontinence products or feminine hygienesanitary pads, and the like which are placed against or in proximity tothe body of the wearer to absorb and contain exudates discharged fromthe body. The absorbent articles of the invention will be furtherillustrated in the below description and in the Figures in the form of ataped diaper. Nothing in this description should be however consideredlimiting the scope of the claims unless explicitly indicated otherwise.

A “nonwoven web” as used herein means a manufactured sheet, web orbatting of directionally or randomly orientated fibers, bonded byfriction, and/or cohesion and/or adhesion, excluding paper and productswhich are woven, knitted, tufted, stitch-bonded incorporating bindingyarns or filaments, or felted by wet-milling, whether or notadditionally needled. The fibers may be of natural or man-made originand may be staple or continuous filaments or be formed in situ.Commercially available fibers have diameters ranging from less thanabout 0.001 mm to more than about 0.2 mm and they come in severaldifferent forms such as short fibers (known as staple, or chopped),continuous single fibers (filaments or monofilaments), untwisted bundlesof continuous filaments (tow), and twisted bundles of continuousfilaments (yarn). Nonwoven webs can be formed by many processes such asmeltblowing, spunbonding, solvent spinning, electrospinning, carding andairlaying. The basis weight of nonwoven webs is usually expressed ingrams per square meter (g/m² or gsm).

Absorbent Cores

The absorbent cores of the invention will be typically made to be usedin an absorbent article. The absorbent core may for example be madeon-line and assembled directly with the remaining components of thearticle or may be off-line at another site and transported to theconverting line. It is also possible to use the absorbent core directlyas an absorbent article without further assembling of other componentsfor applications which do not require other layers. Typically howeverthe absorbent core will be assembled with other components such as atopsheet and a backsheet to form a finished absorbent article, as willbe described further below using a diaper as an example. The absorbentcore may be generally rectangular or may be shaped. In certainembodiments, the absorbent core is substantially hour-glass shaped, inthe longitudinal direction. In further embodiments, the absorbentmaterial deposition area (discussed below) may be shaped, and may besubstantially hour-glass shaped.

The absorbent core is typically the component of the article having themost absorbent capacity. The absorbent core of the invention comprises acore wrap enclosing an absorbent material, and may also comprise atleast one adhesive. The absorbent material comprises SAP. The absorbentmaterial may comprise relatively high amounts of SAP enclosed within thecore wrap. By “absorbent material” it is meant a material which has someabsorbency property or liquid retaining properties, such as SAP,cellulosic fibers as well as synthetic fibers. Typically, adhesives usedin making absorbent cores have no absorbency properties and are notconsidered as absorbent material.

The SAP content may represent at least about 87% or more (in particularat least about 90%, at least about 95%, at least about 98%, and up to100%) by weight of the absorbent material enclosed in the core wrap. Thecore wrap itself is not considered as absorbent material for the purposeof assessing the percentage of SAP in the absorbent core. A relativelyhigh amount of SAP will provide a relatively thin core compared toconventional core typically comprising between 40-60% by weight ofcellulosic material. The absorbent core may be thin, for example havinga thickness not exceeding 5 mm, e.g. from 0.2 mm to 4 mm, in particularfrom 0.5 to 3 mm, as measured with the Dry Absorbent Core Caliper Testdisclosed herein.

As discussed above, the inventors have found that it is advantageous tomove wetted SAP at least a certain distance from its original (dry)position in the core in the longitudinal direction or the transversedirection (not in the thickness direction). Without being bound bytheory, it is believed that the cores of the present invention aredesigned to restrict the swelling space available to SAP (in thethickness direction), thus urging it to move or flow (in thelongitudinal and/or transverse directions). To achieve flow (in thetransverse or longitudinal direction) of the swollen SAP, there shouldnot only be provided an urge to flow (stress) via restricting theswelling space as explained above, but also the swollen SAP should becapable of moving relatively easily (“flowing”, e.g. having lowviscosity, and/or low or no yield stress). This may be achieved, e.g.,by avoiding (a) mechanical entanglement of the swollen SAP particles,(b) SAP particles not sticking to each other, (c) SAP particles notsticking to something else in the core, and/or (d) allowing SAPparticles to move in the desired direction by not havingwall/restrictions in that direction.

Mechanical entanglement can be avoided, e.g. by (a) having theappropriate swollen SAP particle morphology, smooth and round leading toless entanglement; (b) not having other materials (such as pulp fibersor other fibers) blended with the SAP particles that promoteentanglement; (c) having the particles loosely packed (rather thancompacted); and/or (d) not compressing the gel bed too much. The skilledperson will recognize that even for easily flowable gels there is adelicate balance between restricting the swelling space in thez-direction and correspondingly compressing the gel bed a bit creatingthe stress that will cause the gel to move, and not restricting theswell space in the z-direction too much such that the gel bed iscompressed so much that the gel particles mechanically entangle and nolonger flow. The inventors found this balance by (a) using core wrapmaterials that have the right stress strain behaviors, and by (b) usingthe right geometries.

Swollen gel particles sticking together can be avoided, e.g., by (a)having particles that have non-tacky surfaces when wet (tacky gels woulde.g. be superabsorbent gels that both have a cationic and an anionicpolymer (such as the mixed bed ion exchange SAP's), (b) not adding highviscosity water soluble fluids (such as glycerine) to the gel bed,and/or (c) avoiding that when the urine evaporates the particles areunder pressure and the salts from the urine “bake” the particlestogether.

Avoiding that particles stick to something else can be achieved, e.g. by(a) not having (fibrous) glue to immobilize the gel particles, (b)having a water solvable glue or other water responsive agent toimmobilize the dry gel particles that will dissolve or otherwisedeteriorate in the presence of urine and not immobilize the wetted gelparticles, and/or (c) not having other tacky when wet material blendedwith the gel or adjacent to the gel.

This may be also be achieved by having low or no adhesive gluing the SAPto the core, including flowable (or non-sticky) SAP in the core,providing a geometry in the core that does not allow wetted SAP movementin certain directions (e.g. placement of walls, barriers, permanentseams, etc.), and combinations thereof. Additionally, the cores of thepresent invention may provide the opportunity for swelled SAP to move ina guided direction. This may be achieved by having open areas beyondsuch walls, barriers, permanent seams, etc. that the wetted SAP may“flow” to. The skilled person will appreciate that the cores do notactually actively move the wetted SAP, rather, the movement of SAPshould be viewed as dry SAP incurring a wetness insult, then swelling asit absorbs the wetness, then the swollen SAP encountering resistancefrom its surroundings, e.g. walls, barriers, permanent seams, etc., andaccordingly, “moving” towards areas of less resistance.

An exemplary absorbent core 28 of the invention is shown in isolation inFIGS. 1-2 and will now be further described. The absorbent core shownand its description are purely for exemplary purpose and are notintended to limit the scope of the claims, unless otherwise stated. Theabsorbent core typically comprises a front side 280, a back side 282 andtwo longitudinal sides 284, 286 joining the front side 280 and the backside 282. The absorbent core also comprises a generally planar top side16 and a generally planar bottom side 16′ formed by the core wrap. Thefront side 280 of the core is the side of the core intended to be placedtowards the front edge 10 of the absorbent article. The core may have alongitudinal axis 80′ corresponding substantially to the longitudinalaxis of the article 80, as seen from the top in a planar view as in FIG.1 . Typically the absorbent material will be advantageously distributedin higher amount towards the front side and middle portion of the corethan towards the back side as more absorbency is required at the front.Typically the front and back sides of the core are shorter than thelongitudinal sides of the core. The core wrap may be formed by twononwoven materials which may be at least partially sealed along thesides of the absorbent core. The first nonwoven may substantially formthe whole of the top side of the core wrap and the second nonwovensubstantially the whole of the bottom side 16′ of the core wrap. The topside and first nonwoven are represented by the same number 16 on thedrawings, the bottom side and the second nonwoven by number 16′. Thecore wrap may be at least partially sealed along its front side, backside and/or two longitudinal sides to improve the containment of theabsorbent material during use.

The absorbent material may in particular comprise less than 10% weightpercent of natural or synthetic fibers, or less than 5% weight percent,or even be substantially free of natural and/or synthetic fibers. Theabsorbent material may advantageously comprise little or no airfelt(cellulose) fibers, in particular the absorbent core may comprise lessthan 15%, 10%, 5% airfelt (cellulose) fibers by weight of the absorbentcore, or even be substantially free of cellulose fibers.

The absorbent core 28 comprises at least one swelling chamber 400delimited by permanent continuous seals 410. When wetted, absorbentmaterial may become mobile within an internal chamber zone 420. Thecontinuous permanent seals 410 prevent absorbent material from passingfrom the internal chamber zone 420 into external zone 430. In suchexternal zones 430, the absorbent material may be immobilized in its wetstate, or the zone 430 may be free or substantially free ofsuperabsorbent polymer, or the absorbent material may be mobile but flowdifferently than absorbent material within the internal chamber zone.

The length L″ of the absorbent core as measured along it axis 80′ fromthe front side 280 to the back side 282 should be adapted for theintended article in which it will be used. The absorbent cores maytypically have a length from 150 mm to 500 mm, and a width from 40 mm to150 mm.

The core may comprise one or more adhesives as discussed below. In someembodiments, the core may comprise about 25% or less, or about 20% orless, or about 15% or less, or from about 0.5% to about 20%, or fromabout 1% to about 15%, or from about 4% to about 13%, or from about 2%to about 10% of adhesive based on the total weight of the core, recitingfor each range every 1% increment therein. The individual components ofthe absorbent core will now be described in further detail.

Core Wrap (16, 16′)

The function of the core wrap is to enclose the absorbent material.Typical core wraps comprise two substrates 16, 16′ which are attached toanother, but the core wrap may also be made of a single substrate foldedaround the absorbent material, or may comprises several substrates. Whentwo substrates are used, these may be typically attached to anotheralong at least part of the periphery of the absorbent core. Typicalattachments are the so-called C-wrap and sandwich wrap. In a C-wrap, asexemplarily shown in FIG. 2 , the longitudinal and/or transversal edgesof one of the substrate are folded over the other substrate to formflaps. These flaps are then bonded to the external surface of the othersubstrate, typically by gluing. In a sandwich wrap, the edges of bothsubstrates are attached, e.g. by gluing, to another in a flatconfiguration.

The core wrap may be formed by any materials suitable for enclosing theabsorbent material. Typical substrate materials used in the productionof conventional cores may be used, in particular nonwovens but alsopaper, tissues, films (including apertured or perforated films), mesh,wovens, or laminate of any of these. The core wrap material may compriseany suitable basis weight. In nonlimiting examples, the substratematerial may have a basis weight of at least about 5 gsm, or at leastabout 8 gsm, or at least about 10 gsm, or from about 5 gsm to about 30gsm, or from about 8 gsm to about 25 gsm, reciting for each range every1 gsm increment therein. In other nonlimiting examples, the substratematerial may have a basis weight of about 60 gsm or greater, or about 70gsm or greater, or about 80 gsm or greater. The basis weight and type ofmaterial can be selected to ensure the right stress strain profile forthe invention.

The core wrap may in particular be formed by a nonwoven web, such as acarded nonwoven, a spunbond nonwoven (“S”) or a meltblown nonwoven(“M”), and laminates of any of these. For example spunmelt polypropylenenonwovens are suitable, in particular those having a laminate web SMS,or SMMS, or SSMMS, structure. Suitable materials are for exampledisclosed in U.S. Pat. No. 7,744,576, US2011/0268932A1, US2011/0319848A1or US2011/0250413A1. Nonwoven materials provided from synthetic fibersmay be used, such as PE, PET and in particular PP. Elastic fibers may beused as well. Suitable substrates may be elastomeric. In particular, thesubstrate on the garment-facing side of the absorbent core may beelastomeric. In such instances, it may be advantageous to partiallyattach such elastomeric layer to the backsheet to ensure the desiredextensibility in the final product.

The core wrap may be liquid permeable. If the core wrap comprises afirst substrate 16 and a second substrate 16′ these may be made of thesame type of material, or may be made of different materials or one ofthe substrate may be treated differently than the other to provide itwith different properties. One or both of the substrates may comprise aliquid permeable layer. As some of the polymers used for nonwovenproduction are inherently hydrophobic, they are preferably coated withhydrophilic coatings if placed on the fluid receiving side of theabsorbent core. It may be advantageous that the top side 16 of the corewrap, i.e. the side placed closer to the wearer in the absorbentarticle, be more hydrophilic than the bottom side 16′ of the core wrap.A possible way to produce nonwovens with durably hydrophilic coatings isvia applying a hydrophilic monomer and a radical polymerizationinitiator onto the nonwoven, and conducting a polymerization activatedvia UV light resulting in monomer chemically bound to the surface of thenonwoven. An alternative possible way to produce nonwovens with durablyhydrophilic coatings is to coat the nonwoven with hydrophilicnanoparticles, e.g. as described in WO 02/064877.

Permanently hydrophilic nonwovens are also useful in some embodiments.Surface tension can be used to measure how permanently a certainhydrophilicity level is achieved. Liquid strike through can be used tomeasure the hydrophilicity level. The first and/or second substrate mayin particular have a surface tension of at least 55, preferably at least60 and most preferably at least 65 mN/m or higher when being wetted withsaline solution. The substrate may also have a liquid strike throughtime of less than 5 seconds for a fifth gush of liquid. These values canbe measured using the test methods described in U.S. Pat. No.7,744,576B2 (Busam et al.): “Determination Of Surface Tension” and“Determination of Strike Through” respectively.

Hydrophilicity and wettability are typically defined in terms of contactangle and the strike through time of the fluids, for example through anonwoven fabric. This is discussed in detail in the American ChemicalSociety publication entitled “Contact angle, wettability and adhesion”,edited by Robert F. Gould (Copyright 1964). A substrate having a lowercontact angle between the water and the surface of substrate may be saidto be more hydrophilic than another.

The substrates may also be air-permeable Films useful herein maytherefore comprise micro-pores. The substrate may have for example anair-permeability of from 40 or from 50, to 300 or to 200 m³/(m²×min), asdetermined by EDANA method 140-1-99 (125 Pa, 38.3 cm²). The material ofthe core wrap may alternatively have a lower air-permeability, e.g.being non-air-permeable, for example to facilitate handling on a movingsurface comprising vacuum.

The core wrap may be sealed along its longitudinal edges and/or itstransversal edges. In a C-wrap configuration, for example, a firstsubstrate 16 may be placed on one side of the core and extends aroundthe core's longitudinal edges to partially wrap the opposed bottom sideof the core (see FIG. 2 ). The second substrate 16′ is typically presentbetween the wrapped flaps of the first substrate 16 and the absorbentmaterial 60. The flaps of the first substrate 16 may be glued to thesecond substrate 16′ to provide a strong seal. This so called C-wrapconstruction can provide benefits such as improved resistance tobursting in a wet loaded state compared to a sandwich seal. The frontside and back side of the core wrap may then also be sealed for exampleby gluing the first substrate and second substrate to another to providecomplete enclosing of the absorbent material across the whole of theperiphery of the core. For the front side and back side of the core thefirst and second substrate may extend and be joined together in asubstantially planar direction, forming for these edges a so-calledsandwich construction. In the so-called sandwich construction, the firstand second substrates may also extend outwardly on all sides of the coreand be sealed flat along the whole or parts of the periphery of the coretypically by gluing and/or heat/pressure bonding. Typically neitherfirst nor second substrates need to be shaped, so that they can berectangularly cut for ease of production but of course other shapes arepossible.

The terms “seal” and “enclosing” are to be understood in a broad sense.The seal does not need to be continuous along the whole periphery of thecore wrap but may be discontinuous along part or the whole of it, suchas formed by a series of seal points spaced on a line. Typically a sealmay be formed by gluing, thermal bonding, ultrasonic bonding, and/orpressure bonding/crimping. The core wrap may also be formed by a singlesubstrate which may enclose the absorbent material as in a parcel wrapand be for example sealed along the front side and back side of the coreand one longitudinal seal.

Absorbent Material 60

The absorbent core 28 comprises an absorbent material 60 comprising SAP.The absorbent material may be for example applied as a continuous layer.The absorbent material may also be comprised of individual pockets orstripes of absorbent material enclosed within the core wrap.

The absorbent material may be disposed within frangible pockets 100 asshown in FIG. 3 . In certain embodiments, the internal chamber zone 420comprises absorbent material disposed in frangible pockets 100 in a drystate. The pockets may be substantially surrounded by circumscribingbonds 110 (depicted as the grid-like lines in FIG. 3 ) formed by waterresponsive immobilizing agents 50, which water responsive agents may beselected from the group consisting of: adhesive bonds, water solublebonds, bonds formed by heat fusion, ultrasound, pressure, mechanical, orcrimping, and combinations thereof. The bonds may be water responsive,i.e., weaken or deteriorate upon exposure to water, in particular atleast 5 ml of water. The circumscribing bonds may join the top substratelayer 16 to the bottom substrate layer 16′ prior to liquid insult.

The absorbent material may otherwise be immobilized by water responsiveimmobilizing agents, in forms other than frangible pockets. In someembodiments, the water responsive immobilizing agent may be in the formof fibers, such as a fibrous water soluble adhesive.

In some embodiments, a continuous layer of absorbent material, inparticular of SAP, may also be obtained by combining two absorbentlayers having matching discontinuous absorbent material applicationpattern wherein the resulting layer is substantially continuouslydistributed across the absorbent particulate polymer material area, astaught in US2008/0312622A1 (Hundorf) for example. In this way, eachabsorbent material layer comprises a pattern having absorbent materialareas and absorbent material-free areas, wherein the absorbent materialareas of the first layer correspond substantially to the absorbentmaterial-free areas of the second layer and vice versa. A microfibrousglue 51 as disclosed further below may optionally be applied on aportion of each absorbent material layer to immobilize it on eachsubstrate. The microfibrous glue 51 may be applied, for example, in theexternal zone 430.

As exemplary shown in FIG. 4 , a portion of the absorbent core 28 maythus comprise a first absorbent layer and a second absorbent layer, thefirst absorbent layer comprising a first substrate 16 and a first layer61 of absorbent material, which may be 100% SAP, and the secondabsorbent layer comprising a second substrate 16′ and a second layer 62of absorbent material, which may also be 100% SAP. The first and secondSAP layers may be applied as transversal stripes or “land areas” havingthe same width as the desired absorbent material deposition area 8 ontheir respective substrate before being combined. The stripes mayadvantageously comprise different amount of absorbent material toprovide a profiled basis weight along the longitudinal axis and/ortransversal axis of the core 80′. The first substrate 16 and the secondsubstrate 16′ may form the core wrap. An auxiliary glue 71, 72 may beapplied between one or both substrates and the absorbent layers, as wellas microfiber glue on each absorbent layer.

Superabsorbent Polymer Particles (SAP)

“Superabsorbent polymers” as used herein refer to absorbent materialwhich are cross-linked polymeric materials that can absorb at least 10times their weight of an aqueous 0.9% saline solution as measured usingthe Centrifuge Retention Capacity (CRC) test (EDANA method WSP241.2-05E). These polymers are typically used in particulate forms(“SAP”) so as to be flowable in the dry state. The term “particles”refers to granules, fibers, flakes, spheres, powders, platelets andother shapes and forms known to persons skilled in the art ofsuperabsorbent polymer particles.

Typical particulate absorbent polymer materials are made ofpoly(meth)acrylic acid polymers. However, e.g. starch-based particulateabsorbent polymer material may also be used, as well polyacrylamidecopolymer, ethylene maleic anhydride copolymer, cross-linkedcarboxymethylcellulose, polyvinyl alcohol copolymers, cross-linkedpolyethylene oxide, and starch grafted copolymer of polyacrylonitrile.The superabsorbent polymer may be polyacrylates and polyacrylic acidpolymers that are internally and/or surface cross-linked. Thesuperabsorbent polymers can be internally cross-linked, i.e. thepolymerization is carried out in the presence of compounds having two ormore polymerizable groups which can be free-radically copolymerized intothe polymer network. Exemplary superabsorbent polymer particles of theprior art are for example described in WO2006/083584, WO2007/047598,WO2007/046052, WO2009/155265, WO2009/155264.

At least some of the superabsorbent polymers may be present in the formof agglomerated superabsorbent polymer particles. Agglomeratedsuperabsorbent polymer particles comprise agglomerated precursorparticles having a first mass average particle size, and wherein theagglomerated superabsorbent polymer particles have a second mass averageparticle size which is at least 25% greater than the first mass averageparticle size. The second mass average particle size may be at least30%, or at least 40% or at least 50% higher than the first mass averageparticle size.

The agglomerated superabsorbent polymer particles may be obtained byvarious methods. Agglomerated particles may be for example obtained byaggregating the precursor particles with an interparticle crosslinkingagent reacted with the polymer material of the precursor particles toform crosslink bonds between the precursor particles have been forexample disclosed in U.S. Pat. Nos. 5,300,565, 5,180,622, (both toBerg), U.S. Pat. Nos. 5,149,334, 5,102,597 (both to Roe), U.S. Pat. No.5,492,962 (Lahrman). Agglomerated superabsorbent polymer particles mayalso be obtained by a method comprising the steps of providingsuperabsorbent polymer particles and mixing the superabsorbent polymerparticles with a solution comprising water and a multivalent salt havinga valence of three or higher. This method is further disclosed inEP14168064.

The superabsorbent polymer particles of the core of the invention may inparticular comprise at least 10%, or at least 20% or at least 30% or atleast 50% by weight of the agglomerated superabsorbent polymerparticles.

The total amount of SAP present in the absorbent core may also varyaccording to expected user of the article. Diapers for newborns requireless SAP than infant or adult incontinence diapers. In nonlimitingexamples, the absorbent core may comprise from about 2 to about 50 g, orabout 3 to about 40 g, or 5 to about 25 g, or from about 6 g to about 20g, or from about 8 g to about 15 g, of superabsorbent polymer, recitingfor every range each 2 g increment therein. The average SAP basis weightwithin the (or “at least one”, if several are present) deposition area 8of the SAP may be for example of at least about 100, 200, 300, 400, 500,700 or more, or about 1000 or less, or about 900 or less g/m². Thematerial free areas 26 present in the absorbent material deposition area8 are deducted from the absorbent material deposition area to calculatethis average basis weight. The Ball Breakthrough (BB) value of a swollenlayer of the SAP composition can provide a measure of the integrity ofthe layer of the SAP composition in the swollen state, which may providea measure of the SAP's stickiness, or conversely, its ability to flow.The BB is the force (peak load, in grams force) required to rupture alayer of an SAP composition that is swollen in synthetic urine solution,under specific conditions. In a Ball Breakthrough measurement, a 1.0 gsample of the absorbent polymer composition is allowed to absorb 30 mLof synthetic urine solution to form a swollen gel layer. The forcerequired to rupture the layer with a ball-shaped stainless steel probeis the Ball Breakthrough of the material. The method for determiningBall Breakthrough of SAP's is described in detail in the Test Methodssection below. As is discussed above, a relatively low Ball Breakthroughindicates good flowability of a layer comprising a high concentration ofSAP.

SAP's for use in the present invention may be described in terms oftheir ability to exhibit an integrity that allows flowability in theswollen state. In this regard, such SAP's may exhibit a BB from 0 gf to50 gf, preferably from 0 gf to 25 gf. Good integrity of the SAP may beachieved, e.g. by varying certain ingredients/processes of an SAP tomake it more flowable. Additionally or alternatively, SAP may have avalue of absorption against pressure (AAP) of about 15 g/g or more,and/or about 45 g/g or less, or from about 15 g/g to about 45 g/g, orfrom about 20 g/g to about 40 g/g as measured with an Absorption AgainstPressure Test Method, reciting for each range every 5 g/g incrementtherein.

Absorbent Material Deposition Area 8

The absorbent material deposition area 8 can be defined by the peripheryof the layer formed by the absorbent material 60 within the core wrap,as seen from the top side of the absorbent core. The absorbent materialdeposition area 8 can be generally rectangular, for example, but othershapes can also be used such as a “T” or “Y” or “sand-hour” or“dog-bone” shape. In particular the deposition area may show a taperingalong its width towards the middle or “crotch” region of the core. Inthis way, the absorbent material deposition area may have a relativelynarrow width in an area of the core intended to be placed in the crotchregion of the absorbent article. This may provide for example betterwearing comfort. The absorbent material deposition area 8 may thus havea minimum width (as measured in the transversal direction) at itsnarrowest point which is less than about 100 mm, 90 mm, 80 mm, 70 mm, 60mm or even less than about 50 mm. This minimum width may further be forexample at least 5 mm, or at least 10 mm, smaller than the maximum widthof the deposition area at its widest point in the front and/or backregions of the deposition area 8. The deposition area may be segmented;for instance, portions may comprise absorbent material immobilized withwater responsive immobilizing agents and portions may comprise absorbentmaterial immobilized with materials that do not deteriorate or detachupon exposure to water (e.g., thermoplastic adhesive).

The basis weight (amount deposited per unit of surface) of the SAP mayalso be varied along the deposition area 8 to create a profileddistribution of absorbent material, in particular SAP, in thelongitudinal direction, in the transversal direction, or both directionsof the core. Hence along the longitudinal axis of the core, the basisweight of absorbent material may vary, as well as along the transversalaxis, or any axis parallel to any of these axes. The basis weight of SAPin area of relatively high basis weight may thus be for example at least10%, or 20%, or 30%, or 40%, or 50% higher than in an area of relativelylow basis weight. In particular, the SAP present in the absorbentmaterial deposition area at the longitudinal position of the crotchpoint C′ may have more SAP per unit of surface deposited as compared toanother area of the absorbent material deposition area 8, particularlyin a dry state.

The absorbent material may be deposited using known techniques, whichmay allow relatively precise deposition of SAP at relatively high speed.In particular the SAP printing technology as disclosed for example inUS2006/024433 (Blessing), US2008/0312617 and US2010/0051166A1 (both toHundorf et al.) may be used. This technique uses a transfer device suchas a printing roll to deposit SAP onto a substrate disposed on a grid ofa support which may include a plurality of cross bars extendingsubstantially parallel to and spaced from one another so as to formchannels extending between the plurality of cross-bars. This technologyallows high-speed and precise deposition of SAP on a substrate inparticular to provide one or more area(s) 26 substantially free ofabsorbent material surrounded by, or adjacent to, absorbent material.The areas substantially free of absorbent material can be formed forexample by modifying the pattern of the grid and receiving drums so thatno SAP is applied in the selected areas, as exemplary disclosed inUS2012/0312491 (Jackels). In nonlimiting examples, the areas 26substantially free of absorbent material may coincide with permanentseal(s) 410 forming swelling chambers 400.

Area(s) 26 Substantially Free of Absorbent Material and Channels

The absorbent core 28 comprises one or more area(s) 26 which is/aresubstantially free of absorbent material. By “substantially free” it ismeant that in each of these areas the basis weight of the absorbentmaterial is at least less than 25%, in particular less than 20%, lessthan 10%, of the average basis weight of the absorbent material in therest of the core. In particular there can be no absorbent material inthese areas. Minimal amount such as involuntary contaminations withabsorbent material that may occur during the making process are notconsidered as absorbent material. The top side 16 of the core wrap isattached to the bottom side 16′ of the core wrap by core wrap bond(s) 27through these area(s) 26 substantially free of absorbent material. Whenthe absorbent material swells upon absorbing a liquid, the core wrapbond remains at least initially attached in the substantially materialfree area(s) 26. In some embodiments, the core wrap bond in the area 26serves as a continuous permanent seal 410, forming a portion of thechamber periphery. The absorbent material swells in the rest of the corewhen it absorbs a liquid, so that the core wrap may form one or morechannel(s) 26 along the area(s) 26 substantially free of absorbentmaterial comprising the core wrap bond. These channels 26 can be threedimensional and can serve to distribute an insulting fluid along theirlength to a wider area of the core. This may provide a quicker fluidacquisition speed and a better utilization of the absorbent capacity ofthe core. The channels 26 can also provide a deformation of an overlyinglayer such as an acquisition-distribution system layer 54 and providecorresponding ditches in the overlying layer. It is not excluded thatthe absorbent core may comprise other area(s) substantially free ofabsorbent material but without a core wrap bond, but these non-bondedareas will typically not form a channel when wet.

The substantially material free area(s) 26 may be present within thecrotch region of the article, in particular at least at the samelongitudinal level as the crotch point C′, as represented in FIGS. 1, 5by the longitudinally extending areas substantially free of absorbentmaterial 26. The absorbent core may comprise one or more pairs of areassubstantially free of absorbent material symmetrically arranged relativeto the longitudinal axis 80′.

The area(s) 26 substantially free of absorbent material may extendsubstantially longitudinally, which means typically that each areaextends more in the longitudinal direction than in the transversedirection, and typically at least twice as much in the longitudinaldirection than in the transverse direction (as measured after projectionon the respective axis). The area(s) 26 substantially free of absorbentmaterial may have a length projected on the longitudinal axis 80′ of thecore that is at least 10% of the length L″ of the absorbent core, inparticular from 20% to 80%. It may be advantageous that at least some orall of the area(s) 26 are not completely or substantially completelytransversely oriented channels in the core.

Swelling Chambers

The absorbent core may comprise one or more swelling chambers 400. Theswelling chamber may be funnel-shaped as shown in FIGS. 6-6M. Theswelling chamber is a portion of the absorbent core containing absorbentmaterial, such as superabsorbent polymer, and being delimited by aplurality of continuous permanent seals 410. In nonlimiting examples,the swelling chamber is delimited by two continuous permanent seals 410.The seals 410 join the top 16 and bottom 16′ layers of the core wrap.The seals 410 may be void of absorbent material (i.e., the seals may bein the form of channels 26). The seals 410 separate absorbent materialinternal chamber zones 420 from external zones 430. The external zones430 may be free from absorbent material, may comprise absorbent materialwhich is immobilized in its wet state, or in some cases, may comprisemobile absorbent material which does not flow in the same manner as inthe internal chamber zone. In this way, wet absorbent material withinthe chamber may flow within the internal chamber zones 420 but beprevented from entering the external zones 430.

The external zones may be disposed adjacent to a side of the core (e.g.,284, 286). In certain embodiments, the external zone is disposedadjacent to an edge of the absorbent material deposition area 8, whichedge may be set apart from a side of the core as illustrated for examplein FIG. 1 . In nonlimiting examples, one or more continuous permanentseals delimiting the swelling chamber may extend to a side of theabsorbent material deposition area, or may be within 10 mm or less, or 5mm or less, or 2 mm from the most proximate side. In some embodiments,the permanent seals 410 delimiting the swelling chamber do not extend toa side of the core. In further examples, the permanent seals may extendto some but not all sides, as shown for example in FIG. 6 .

The swelling chamber may be open on one or more ends, meaning theplurality of continuous permanent bonds are discrete (i.e.,disconnected) at said end. FIGS. 6-6M show embodiments having chamberswith open ends. In some embodiments, one or more chamber ends may beclosed. In such embodiments, the closed end may be formed by onecontinuous permanent bond that forms said end or by the joining ofmultiple permanent seals at such end to close the chamber. Innonlimiting examples, the chamber may be open on one end and closed onanother end, such as an opposing end.

The continuous permanent seals may be formed by a suitable bondingmeans, including but not limited to adhesive, ultrasonic bonding, heatbonding, pressure bonding, mechanical bonding or combinations thereof.

In certain embodiments, one or more continuous permanent seals arelongitudinally extending, having a longitudinal dimension that exceedsthe transverse dimension, and typically at least twice as much in thelongitudinal direction than in the transverse direction (as measuredafter projection on the respective axis). It is also contemplated thatone or more permanent seals are transversely-extending, having atransverse dimension that exceeds the longitudinal dimension, typicallyby at least twice the longitudinal dimension. The permanent seals mayhave any suitable width, provided the seal sufficiently serves toprevent absorbent material, in particular superabsorbent polymermaterial, from passing from the internal chamber zone 420 into theexternal zones 430 in the area where the seal is present.

The length of the chamber (L_(CH)) is measured as the greatest distancebetween end points of permanent seals in the major dimension of thechamber (i.e., length would be the maximum longitudinal distance if thechamber is longitudinally extending), and width (W_(CH)) is the averagedistance between two permanent seals in the direction perpendicular tothe length. The width of the chamber may be from about 20% to about 50%of the width of the core, reciting for said range every 5% incrementtherein. In nonlimiting examples, the width of the chamber is from about2 cm to about 5 cm, reciting for said range every 0.5 cm incrementtherein. Additionally, the swelling chamber has an area that is lessthan the area of the core. In nonlimiting examples, the area of the coreis at least about 1.5 times greater, or at least about 2 times greater,or from about 1 times to about 3 times greater than the area of theswelling core.

Permanent seals, or portions thereof, may be substantially straight.Permanent seals, or portions thereof, may be disposed at an angle withrespect to the longitudinal axis and/or with respect to the transverseaxis. Permanent seals may be curved or comprise curved portions. Thepermanent seals may form walls that are concave with respect to thelongitudinal axis of the core.

In certain embodiments, two permanent seals may be substantiallyparallel and/or may be substantially mirror images for a least a portionof their respective lengths. In nonlimiting examples, two permanentseals are substantially parallel and/or substantially mirror images forat least 25% of the length of the shortest of the two seals, or at least50% of the length of the shortest of the two seals, or from about 25% toabout 100% of the length of the shortest of the two seals, reciting forsaid range every 5% increment therein.

As shown in FIGS. 6-6A, the funnel-shaped chamber may be formed byopposing funnel wall segments 440 a, 440 b, where the wall segmentsoppose one another across the major axis of the chamber (i.e., opposingfunnel wall segments of a longitudinally-extending chamber oppose oneanother across the longitudinal axis). The opposing wall segments eachform an angle with respect to the major axis. For example, in FIG. 6 ,the chamber comprises first opposing wall segments, wherein wall segment440 a which forms an angle α with respect to a line parallel to thelongitudinal axis, and wall segment 440 b forms an angle γ with respectto a line parallel to the longitudinal axis. Where the wall segment iscurved, the angle is determined by the imaginary line extending betweenthe converging point, CP, of the permanent seal and the furthermostpoint on the opposing edge of the segment as shown in FIG. 6A. Theconverging point, CP, is the point of the segment most proximate to themajor axis.

The chamber may further comprise a second opposing wall segments 450 a,450 b, each forming an angle with respect to the major axis of thechamber. As illustrated in FIGS. 6-6A, the second opposing wall segmentsmay form angles 13 and 6, respectively.

Opposing wall segments may form the same angle or different angles withrespect to the axis (e.g., α and γ may be the same or may be different).The wall segment angles α, β, γ, δ may each be from about 5 degrees toabout 80 degrees, or from about 10 degrees to about 75 degrees, or fromabout 15 degrees to about 60 degrees, reciting for each range every 5degree increment therein.

Opposing wall segments may collectively comprise a chamber angle, thechamber angle being the sum of the individual angles formed by eachopposing wall segment with respect to the major axis. Suitable chamberangles may be from about 20 degrees to about 120 degrees, or from about30 degrees to about 110 degrees, reciting for each range every 10 degreeincrement therein. For instance, a first chamber angle is the sum ofindividual angles (α, γ) formed by first opposing wall segments 440 a,440 b. Likewise, a second chamber angle is the sum of individual angles(β, δ) formed by second opposing wall segments 450 a, 450 b. The firstand second chamber angles may be substantially the same or they may bedifferent from one another. For purposes of the chamber angles,substantially the same means within 5 degrees.

Two wall segments may be formed by the same continuous permanent seal.It is also contemplated two permanent seals may converge, connect orcome with 2 mm of one another to form a boundary of the chamber 400.

Fibrous Adhesive Material 51

The absorbent core may optionally comprise a fibrous adhesive material,in particular a microfiber glue, to further immobilize a portion of theabsorbent material within the core. The fibrous adhesive material may bea fibrous thermoplastic adhesive material 51, which may immobilize SAPin the dry and wet state. Suitable fibrous thermoplastic adhesivematerials are disclosed in U.S. application Ser. No. 13/491,642 toRosati. In some nonlimiting examples, a fibrous adhesive material may beutilized in a permanent seal.

However, it is also contemplated that in certain embodiments, theabsorbent cores enable SAP immobilization at a sufficiently high degreethat a fibrous thermoplastic adhesive material is not needed. In theseembodiments, the absorbent cores, or portions of the absorbent cores, ofthe invention do not contain a fibrous thermoplastic adhesive material.

Auxiliary Glue 71, 72

The absorbent core of the invention may further comprise an auxiliaryglue present on the inner surface of the top side and/bottom side of theabsorbent core in one or more portions of the absorbent core, inparticular to help immobilizing the SAP within the core wrap in theexternal zone, to ensure integrity of the core wrap and/or to form thebond attaching the bottom side of the core wrap to the top side of thecore wrap to form a permanent seal 410.

Example of glues are based on an adhesive polymer such SIS(Styrene-Isoprene-Block Co-Polymer), SBS (Styrene-Butadiene-BlockCo-polymer) or mPO (metalocine Polyolefine). The glue may also comprisea tackifier such as a hydrogenated hydrocarbon resin, as well as an oiland an antioxidant. Hydrogenated hydrocarbon resins are made from mixedaromatic/aliphatic resins which are subsequently selectivelyhydrogenated to produce a wide range of materials with low color, highstability and broad compatibility. Examples of commercially availableadhesives are available as HL1358LO and NW1286 (both from HB Fuller) andDM 526 (from Henkel).

This so-called auxiliary glue 71, 72 can be applied on the inner surfaceof the top side and/or the bottom side of the core wrap. The auxiliaryglue may be any conventional glue used in the field, in particularhotmelt glue. The auxiliary glue may be applied on the top side and/orthe bottom side of the core wrap in an average amount ranging from 2 gsmto 20 gsm, more particularly from 4 gsm to 10 gsm. The auxiliary gluemay be uniformly applied, or discontinuously, in particular as a seriesof stripes regularly spaced and longitudinally oriented, for example aseries of auxiliary glue stripes of about 1 mm width spaced from eachother by a distance ranging from 1 mm to 3 mm. The auxiliary glue mayhelp forming the core wrap bond if sufficient pressure and glue isapplied within the material free area 26 to attach both sides of thecore wrap. The auxiliary glue layer may be applied to the inner surfaceof the bottom side, the inner surface of the top side, or both innersurfaces of the core wrap.

Absorbent Articles

The absorbent cores of the invention may be disposed in absorbentarticles, e.g. as discussed and further illustrated in the form of ababy diaper 20 in FIG. 5 . FIG. 5 is a plan view of the exemplary diaper20, in a flattened state, with portions of the structure being cut-awayto more clearly show the construction of the diaper 20. This diaper 20is shown for illustration purpose only as the invention may be used formaking a wide variety of diapers or other absorbent articles.

The absorbent article comprises a liquid permeable topsheet 24, a liquidimpermeable backsheet 25, and an absorbent core 28 between the topsheet24 and the backsheet 25. An optional acquisition-distribution system 54is represented on FIG. 5 , which also shows other typical taped diapercomponents such as a fastening system comprising adhesive tabs 42attached towards the back edge of the article and cooperating with alanding zone 44 on the front of the article, barrier leg cuffs 34 andelasticized gasketing cuffs 32 joined to the chassis of the absorbentarticle, typically via the topsheet and/or backsheet, and substantiallyplanar with the chassis of the diaper. The absorbent article may alsocomprise other typical elements, which are not represented, such as aback elastic waist feature, a front elastic waist feature, transversebarrier cuff(s), a lotion application, graphics, wetness indicators,etc.

The absorbent article 20 comprises a front edge 10, a back edge 12, andtwo side (longitudinal edges) 13, 14. The front edge 10 of the articleis the edge which is intended to be placed towards the front of the userwhen worn, and the back edge 12 is the opposite edge of the article. Theabsorbent article may be notionally divided by a longitudinal axis 80extending from the front edge to the back edge of the article anddividing the article in two substantially symmetrical halves relative tothis axis, with article placed flat and viewed from above as in FIG. 5 .The length L of the article can be measured along the longitudinal axis80 from front edge 10 to back edge 12. The article comprises a crotchpoint C defined herein as the point placed on the longitudinal axis at adistance of two fifth (⅖) of L starting from the front edge 10 of thearticle 20. The width of the article for a diaper application at thecrotch point may in particular be of from 50 mm to 300 mm, or from 80 mmto 250 mm. For adult incontinence products the width may go up to 450mm.

The crotch region can be defined as the region of the diaperlongitudinally centered at the crotch point C and extending towards thefront and towards the back of the absorbent article by a distance of onefifth of L (L/5) in each direction. A front region and a back region canbe defined as the remaining portions of the diapers placed respectivelytowards the front and the back edges of the article.

The topsheet 24, the backsheet 25, the absorbent core 28 and the otherarticle components may be assembled in a variety of knownconfigurations, in particular by gluing or heat embossing. Exemplarydiaper configurations are described generally in U.S. Pat. Nos.3,860,003, 5,221,274, 5,554,145, 5,569,234, 5,580,411, and 6,004,306.The absorbent article is preferably thin. The caliper at the crotchpoint C of the article may be for example from 3.0 mm to 12.0 mm, inparticular from 4.0 mm to 10.0 mm, as measured with the AbsorbentArticle Caliper Test described herein.

For most absorbent articles, the liquid discharge occurs predominatelyin the front half of the article, in particular for diaper. The fronthalf of the article (as defined by the region between the front edge anda transversal line 90 placed at a distance of half L from the front orback edge may therefore comprise most of the absorbent capacity of thecore. Thus, at least 60% of the SAP, or at least 65%, 70%, 75% or 80% ofthe SAP may be present in the front half of the absorbent article, theremaining SAP being disposed in the back half of the absorbent article.As the absorbent article of the present invention has the ability tomove the gel away from the crotch during use an execution may even have100% of the SAP in the front half of the absorbent article, or have upto 100% in the crotch region of the absorbent article.

The absorbent article may have an acquisition time for the first gush ofless than 30 s, preferably less than 27 s, as measured according to theFlat Acquisition test method set out in WO2012/174026A1. Thisacquisition time may be in measured in particular on a baby diaper whichis designated for wearers having a weight in the range of 8 to 13 kg±20%(such as Pampers Active Fit size 4 or other Pampers baby diapers size 4,Huggies baby diapers size 4 or baby diapers size 4 of most othertradenames).

Topsheet 24

The topsheet 24 is the layer of the absorbent article that is destinedto be in contact with the wearer's skin. The topsheet 24 can be joinedto the backsheet 25, the core 28 and/or any other layers as is known inthe art. Usually, the topsheet 24 and the backsheet 25 may be joineddirectly to each other on or close to the periphery of the article andare indirectly joined together in other locations by directly joiningthem to one or more other elements of the article 20. The topsheet maybe attached to an underlying layer 54, which may be an acquisitionand/or distribution layer, by any conventional means, in particulargluing, mechanical or heat bonding and combinations thereof. Thetopsheet may in particular be attached directly or indirectly to theacquisition-distribution system 54 (if present) in the area where theditches are formed. This may provide or help the formation of secondaryditches at the surface of the article.

The topsheet 24 is preferably compliant, soft-feeling, andnon-irritating to the wearer's skin. Further, at least a portion of thetopsheet 24 is liquid permeable, permitting liquids to readily penetratethrough its thickness. A suitable topsheet may be manufactured from awide range of materials, such as porous foams, reticulated foams,apertured plastic films, or woven or nonwoven materials of naturalfibers (e.g., wood or cotton fibers), synthetic fibers or filaments(e.g., polyester or polypropylene or bicomponent PE/PP fibers ormixtures thereof), or a combination of natural and synthetic fibers. Ifthe topsheet includes fibers, the fibers may be spunbond, carded,wet-laid, meltblown, hydroentangled, or otherwise processed as is knownin the art, in particular spunbond PP nonwoven. A suitable topsheetcomprising a web of staple-length polypropylene fibers is manufacturedby Veratec, Inc., a Division of International Paper Company, of Walpole,MA under the designation P-8.

Suitable formed film topsheets are also described in U.S. Pat. Nos.3,929,135, 4,324,246, 4,342,314, 4,463,045, and 5,006,394. Othersuitable topsheets may be made in accordance with U.S. Pat. Nos.4,609,518 and 4,629,643 issued to Curro et al. Such formed films areavailable from The Procter & Gamble Company of Cincinnati, Ohio as“DRI-WEAVE” and from Tredegar Corporation, based in Richmond, VA, as“CLIFF-T”.

Any portion of the topsheet 24 may be coated with a lotion as is knownin the art. Examples of suitable lotions include those described in U.S.Pat. Nos. 5,607,760, 5,609,587, 5,635,191, 5,643,588, 5,968,025 and6,716,441. The topsheet 24 may also include or be treated withantibacterial agents, some examples of which are disclosed in PCTPublication WO95/24173. Further, the topsheet 24, the backsheet 25 orany portion of the topsheet or backsheet may be embossed and/or mattefinished to provide a more cloth like appearance.

The topsheet 24 may comprise one or more apertures to ease penetrationof exudates therethrough, such as urine and/or feces (solid, semi-solid,or liquid). The size of at least the primary aperture is important inachieving the desired waste encapsulation performance. If the primaryaperture is too small, the waste may not pass through the aperture,either due to poor alignment of the waste source and the aperturelocation or due to fecal masses having a diameter greater than theaperture. If the aperture is too large, the area of skin that may becontaminated by “rewet” from the article is increased. Typically, thetotal area of the apertures at the surface of a diaper may have an areaof between about 10 cm² and about 50 cm², in particular between about 15cm² and 35 cm². Examples of apertured topsheet are disclosed in U.S.Pat. No. 6,632,504, assigned to BBA NONWOVENS SIMPSONVILLE.WO2011/163582 also discloses suitable colored topsheet having a basisweight of from 12 to 18 gsm and comprising a plurality of bonded points.Each of the bonded points has a surface area of from 2 mm² to 5 mm² andthe cumulated surface area of the plurality of bonded points is from 10to 25% of the total surface area of the topsheet. Typical diapertopsheets have a basis weight of from about 10 to about 28 gsm, inparticular between from about 12 to about 18 gsm but other basis weightsare possible.

Backsheet 25

The backsheet 25 is generally that portion of the absorbent article 20which forms the majority of the external surface of the article whenworn by the user. The backsheet is positioned towards the bottom side ofthe absorbent core and prevents the exudates absorbed and containedtherein from soiling articles such as bedsheets and undergarments. Thebacksheet 25 is typically impermeable to liquids (e.g. urine). Thebacksheet may for example be or comprise a thin plastic film such as athermoplastic film having a thickness of about 0.012 mm to about 0.051mm Exemplary backsheet films include those manufactured by TredegarCorporation, based in Richmond, VA, and sold under the trade name CPC2film. Other suitable backsheet materials may include breathablematerials which permit vapors to escape from the diaper 20 while stillpreventing exudates from passing through the backsheet 25. Exemplarybreathable materials may include materials such as woven webs, nonwovenwebs, composite materials such as film-coated nonwoven webs, microporousfilms such as manufactured by Mitsui Toatsu Co., of Japan under thedesignation ESPOIR NO and by Tredegar Corporation of Richmond, VA, andsold under the designation EXAIRE, and monolithic films such asmanufactured by Clopay Corporation, Cincinnati, OH under the name HYTRELblend P18-3097. Some breathable composite materials are described ingreater detail in PCT Application No. WO 95/16746 published on Jun. 22,1995 in the name of E. I. DuPont; U.S. Pat. No. 5,938,648 to LaVon etal., U.S. Pat. No. 4,681,793 to Linman et al., U.S. Pat. No. 5,865,823to Curro; and U.S. Pat. No. 5,571,096 to Dobrin et al, U.S. Pat. No.6,946,585B2 to London Brown.

The backsheet 25 may be joined to the topsheet 24, the absorbent core 28or any other element of the diaper 20 by any attachment means known inthe art. Suitable attachment means are described above with respect tomeans for joining the topsheet 24 to other elements of the article 20.For example, the attachment means may include a uniform continuous layerof adhesive, a patterned layer of adhesive, or an array of separatelines, spirals, or spots of adhesive. Suitable attachment meanscomprises an open pattern network of filaments of adhesive as disclosedin U.S. Pat. No. 4,573,986. Other suitable attachment means includeseveral lines of adhesive filaments which are swirled into a spiralpattern, as is illustrated by the apparatus and methods shown in U.S.Pat. Nos. 3,911,173, 4,785,996; and 4,842,666. Adhesives which have beenfound to be satisfactory are manufactured by H. B. Fuller Company of St.Paul, Minnesota and marketed as HL-1620 and HL 1358-XZP. Alternatively,the attachment means may comprise heat bonds, pressure bonds, ultrasonicbonds, dynamic mechanical bonds, or any other suitable attachment meansor combinations of these attachment means as are known in the art.

Acquisition Distribution System 54

The absorbent article may further comprise an acquisition-distributionsystem that can serve to acquire and distribute the fluid, as illustrateby layer 54 in the Figures. The acquisition-distribution system maycomprise one or more layers which may be present between the topsheet 24and the absorbent core 28, as represented in the Figures, but may bealso between the backsheet 25 and the absorbent core 28, or both. Theacquisition-distribution system 54 may be at least partially bonded tothe top side or the bottom side of the core wrap in the area(s)substantially free of absorbent material. The formation of the channel26 in the absorbent core as the absorbent material swells may thusprovide of one or more corresponding ditches in the at least one of thelayers of the acquisition-distribution system 54.

The acquisition-distribution system layer(s) may be of any kind such asnonwoven, a woven material or even loose fibers. The layers may inparticular be of the type known in the art for acquisition layers and/ordistribution layers. Typical acquisition and/or distribution layers donot comprise SAP as this may slow the acquisition and distribution ofthe fluid, but an acquisition-distribution system may also comprise SAPif some fluid retention properties are wished. The prior art disclosesmany type of acquisition and/or distribution layers that may be used,see for example WO2000/59430 (Daley), WO95/10996 (Richards), U.S. Pat.No. 5,700,254 (McDowall), WO02/067809 (Grad).

A distribution layer can spread an insulting fluid liquid over a largersurface within the article so that the absorbent capacity of the corecan be more efficiently used. Typically distribution layers are made ofa nonwoven material based on synthetic or cellulosic fibers and having arelatively low density. The density of the distribution layer may varydepending on the compression of the article, but may typically rangefrom 0.03 to 0.25 g/cm³, in particular from 0.05 to 0.15 g/cm³ measuredat 0.30 psi (2.07 kPa). The distribution layer may also be a materialhaving a water retention value of from 25 to 60, preferably from 30 to45, measured as indicated in the procedure disclosed in U.S. Pat. No.5,137,537. The distribution layer may typically have an average basisweight of from 30 to 400 g/m², in particular from 100 to 300 g/m².

The distribution layer may comprise a fibrous layer. The distributionlayer may for example comprise at least 50% by weight of cross-linkedcellulose fibers. The cross-linked cellulosic fibers may be crimped,twisted, or curled, or a combination thereof including crimped, twisted,and curled. This type of material has been used in the past indisposable diapers as part of an acquisition system, for example US2008/0312622 A1 (Hundorf). The cross-linked cellulosic fibers providehigher resilience and therefore higher resistance to the first absorbentlayer against the compression in the product packaging or in useconditions, e.g. under a baby's weight. This provides the core with ahigher void volume, permeability and liquid absorption, and hencereduced leakage and improved dryness.

Exemplary chemically cross-linked cellulosic fibers suitable for adistribution layer are disclosed in U.S. Pat. Nos. 5,549,791, 5,137,537,WO9534329 or US2007/118087. Exemplary cross-linking agents includepolycarboxylic acids such as citric acid and/or polyacrylic acids suchas acrylic acid and maleic acid copolymers. In some embodiments, theformation of the channel 26 in the absorbent core as the absorbentmaterial swells provides of one or more corresponding ditches in thedistribution layer.

The absorbent article may also comprise an acquisition layer, whosefunction can be to quickly acquire the fluid away from the topsheet soas to provide a good dryness for the wearer. Such an acquisition layeris typically placed directly under the topsheet. The absorbent articlemay also then comprise a distribution layer typically placed between theacquisition layer and the absorbent core.

The acquisition layer may typically be or comprise a non-woven material,for example a SMS or SMMS material, comprising a spunbonded, amelt-blown and a further spunbonded layer or alternatively a cardedchemical-bonded nonwoven. The non-woven material may in particular belatex bonded. Exemplary upper acquisition layers are disclosed in U.S.Pat. No. 7,786,341. Carded, resin-bonded nonwovens may be used, inparticular where the fibers used are solid round or round and hollow PETstaple fibers (50/50 or 40/60 mix of 6 denier and 9 denier fibers). Anexemplary binder is a butadiene/styrene latex. Non-wovens have theadvantage that they can be manufactured outside the converting line andstored and used as a roll of material. Further useful non-wovens aredescribed in U.S. Pat. Nos. 6,645,569, 6,863,933 (both to Cramer), U.S.Pat. No. 7,112,621 (Rohrbaugh), and co patent applications US2003/148684to Cramer et al. and US2005/008839 (both to Cramer).

Such an acquisition layer may be stabilized by a latex binder, forexample a styrene-butadiene latex binder (SB latex). Processes forobtaining such latexes are known, for example, from EP 149 880 (Kwok)and US 2003/0105190 (Diehl et al.). In certain embodiments, the bindermay be present in the acquisition layer in excess of about 12%, about14% or about 16% by weight. SB latex is available under the trade nameGENFLO™ 3160 (OMNOVA Solutions Inc.; Akron, Ohio).

A further acquisition layer may be used in addition to a firstacquisition layer described above. For example a tissue layer may beplaced between the first acquisition layer and the distribution layer.The tissue may have enhanced capillarity distribution propertiescompared to the acquisition layer described above. The tissue and thefirst acquisition layer may be of the same size or may be of differentsize, for example the tissue layer may extend further in the back of theabsorbent article than the first acquisition layer. An example ofhydrophilic tissue is a 13-22.5 gsm high wet strength made of cellulosefibers from supplier Havix.

If an acquisition layer is present, it may be advantageous that thisacquisition layer is larger than or least as large as an underlyingdistribution layer in the longitudinal and/or transversal dimension. Inthis way the distribution layer can be deposited on the acquisitionlayer. This simplifies handling, in particular if the acquisition layeris a nonwoven which can be unrolled from a roll of stock material. Thedistribution layer may also be deposited directly on the absorbentcore's upper side of the core wrap or another layer of the article.Also, an acquisition layer larger than the distribution layer allows todirectly glue the acquisition layer to the storage core (at the largerareas). This can give increased patch integrity and better liquidcommunication.

However, it is also contemplated that in certain embodiments, theabsorbent cores enable active liquid distribution at a sufficiently highdegree that one or more, or all, layers of an acquisition-distributionsystem are not needed. In these embodiments, the absorbent articlecomprising the absorbent cores of the invention do not contain anacquisition layer and/or do not contain a distribution layer.

Fastening System 42, 44

The absorbent article may include a fastening system, for example as isknown in taped diapers. The fastening system can be used to providelateral tensions about the circumference of the absorbent article tohold the absorbent article on the wearer as is typical for tapeddiapers. An inclined fastening system can also provide tension aroundthe legs of the wearer. This fastening system is not necessary for(training) pant articles since the waist region of these articles isalready bonded. The fastening system usually comprises a fastener suchas tape tabs, hook and loop fastening components, interlocking fastenerssuch as tabs & slots, buckles, buttons, snaps, and/or hermaphroditicfastening components, although any other known fastening means aregenerally acceptable. A landing zone is normally provided on the frontwaist region for the fastener to be releasably attached. Some exemplarysurface fastening systems are disclosed in U.S. Pat. Nos. 3,848,594,4,662,875, 4,846,815, 4,894,060, 4,946,527, 5,151,092 and 5,221,274issued to Buell. An exemplary interlocking fastening system is disclosedin U.S. Pat. No. 6,432,098. The fastening system may also provide ameans for holding the article in a disposal configuration as disclosedin U.S. Pat. No. 4,963,140 issued to Robertson et al.

The fastening system may also include primary and secondary fasteningsystems, as disclosed in U.S. Pat. No. 4,699,622 to reduce shifting ofoverlapped portions or to improve fit as disclosed in U.S. Pat. Nos.5,242,436, 5,499,978, 5,507,736, and 5,591,152.

Barrier Leg Cuffs 34

The absorbent article may comprise a pair of barrier leg cuffs 34 and/orgasketing cuffs 32. U.S. Pat. No. 3,860,003 describes a disposablediaper which provides a contractible leg opening having a side flap andone or more elastic members to provide an elasticized leg cuff (agasketing cuff). U.S. Pat. Nos. 4,808,178 and 4,909,803 issued to Azizet al. describe disposable diapers having “stand-up” elasticized flaps(barrier leg cuffs) which improve the containment of the leg regions.U.S. Pat. Nos. 4,695,278 and 4,795,454 issued to Lawson and to Dragoorespectively, describe disposable diapers having dual cuffs, includinggasketing cuffs and barrier leg cuffs. All or a portion of the barrierleg and/or gasketing cuffs may be treated with a lotion.

The barrier leg cuffs 34 can be formed from a piece of material,typically a nonwoven, which is partially bonded to the rest of thearticle so that a portion of the material, the barrier leg cuffs, can bepartially raised away and stand up from the plane defined by thetopsheet when the article is pulled flat as shown e.g. in FIG. 5 . Thebarrier leg cuffs can provide improved containment of liquids and otherbody exudates approximately at the junction of the torso and legs of thewearer. The barrier leg cuffs extend at least partially between thefront edge and the back edge of the diaper on opposite sides of thelongitudinal axis and are at least present at the longitudinal positionof the crotch point (C). The barrier leg cuffs are delimited by aproximal edge 64 joined to the rest of the article, typically thetopsheet and/or the backsheet, and a free terminal edge 66, which isintended to contact and form a seal with the wearer's skin. The barrierleg cuffs are joined at the proximal edge 64 with the chassis of thearticle by a bond 65 which may be made for example by gluing, fusionbonding or combination of known bonding means. The bond 65 at theproximal edge 64 may be continuous or intermittent. The side of the bond65 closest to the raised section of the barrier leg cuffs 32 delimitsthe proximal edge 64 of the standing up section of the leg cuffs.

The barrier leg cuffs 34 can be integral with the topsheet or thebacksheet, or more typically be formed from a separate material joinedto the rest of the article. Typically the material of the barrier legcuffs may extend through the whole length of the diapers but is “tackbonded” to the topsheet towards the front edge and back edge of thearticle so that in these sections the barrier leg cuff material remainsflush with the topsheet. Each barrier leg cuff 34 may comprise one, twoor more elastic strings 35 close to this free terminal edge 66 toprovide a better seal.

In addition to the barrier leg cuffs 34, the article may comprisegasketing cuffs 32 joined to the chassis of absorbent article, inparticular the topsheet and/or the backsheet and may be placedexternally relative to the barrier leg cuffs. The gasketing cuffs canprovide a better seal around the thighs of the wearer. Usually eachgasketing leg cuff will comprise one or more elastic string or elasticelement comprised in the chassis of the diaper for example between thetopsheet and backsheet in the area of the leg openings.

Front and Back Ears 46, 40

The absorbent article may comprise front ears 46 and back ears 40 as isknown in the art. The ears can be integral part of the chassis, forexample formed from the topsheet and/or backsheet as side panel.Alternatively, as represented on FIG. 1 , they may be separate elementsattached by gluing and/or heat embossing or pressure bonding. The backears 40 are advantageously stretchable to facilitate the attachment ofthe tabs 42 on the landing zone 40 and maintain the taped diapers inplace around the wearer's waist. The back ears 40 may also be elastic orextensible to provide a more comfortable and contouring fit by initiallyconformably fitting the absorbent article to the wearer and sustainingthis fit throughout the time of wear well past when absorbent articlehas been loaded with exudates since the elasticized ears allow the sidesof the absorbent article to expand and contract.

Elastic Waist Feature

The absorbent article may also comprise at least one elastic waistfeature (not represented) that helps to provide improved fit andcontainment. The elastic waist feature is generally intended toelastically expand and contract to dynamically fit the wearer's waist.The elastic waist feature preferably extends at least longitudinallyoutwardly from at least one waist edge of the absorbent core 28 andgenerally forms at least a portion of the end edge of the absorbentarticle. Disposable diapers can be constructed so as to have two elasticwaist features, one positioned in the front waist region and onepositioned in the back waist region. The elastic waist feature may beconstructed in a number of different configurations including thosedescribed in U.S. Pat. Nos. 4,515,595, 4,710,189, 5,151,092 and5,221,274.

Method of Making the Article—Relations Between the Layers

The absorbent articles of the invention may be made by any conventionalmethods known in the art. In particular the articles may be hand-made orindustrially produced at high speed. Typically, adjacent layers andcomponents will be joined together using conventional bonding methodsuch as adhesive coating via slot coating or spraying on the whole orpart of the surface of the layer, or thermo-bonding, or pressure bondingor combinations thereof. This bonding is exemplarily represented for thebond between the leg cuffs 65 and the topsheet 24, and the auxiliaryglues 71, 72 and microfibrous glue 51 on the detail view of theabsorbent core on FIG. 4 . Other glues or attachments are notrepresented for clarity and readability but typical bonding between thelayers of the article should be considered to be present unlessspecifically excluded. Adhesives may be typically used to improve theadhesion of the different layers, for example between the backsheet andthe core wrap. The glue may be any standard hotmelt glue as known in theart.

The absorbent core and in particular its absorbent material depositionarea 8 may advantageously be at least as large and long andadvantageously at least partially larger and/or longer than the fibrouslayer. This is because the absorbent material in the core can usuallymore effectively retain fluid and provide dryness benefits across alarger area than the fibrous layer. The absorbent article may have arectangular SAP layer and a non-rectangular (shaped) fibrous layer. Theabsorbent article may also have a rectangular (non-shaped) fibrous layerand a rectangular layer of SAP.

EXAMPLES

FIGS. 6-6M are illustrations of suitable funnel-shaped swelling chamberdesigns. These cores have funnel-shaped swelling chambers 400, delimitedby permanent seals 410 existing between chamber internal zones 420,wherein SAP is flowable, and external zones 430. Dry SAP may beimmobilized in the flowable areas using any of the techniques describedherein. Wet SAP may flow in the flowable areas but will be preventedfrom escaping a zone by the permanent seals.

Packages

The absorbent articles may be folded and packaged as is known in theart. The package may be for example a plastic bag or a cardboard box.Diapers may typically bi-folded along the transversal axis and the earsfolded inwardly before being packaged. The absorbent articles may bepacked under compression so as to reduce the size of the packages, whilestill providing an adequate amount of absorbent articles per package. Bypackaging the absorbent articles under compression, caregivers caneasily handle and store the packages, while also providing distributionand inventory savings to manufacturers owing to the size of thepackages. FIG. 7 illustrates an example package 1000 comprising aplurality of absorbent articles 1004. The package 1000 defines aninterior space 1002 in which the plurality of absorbent articles 1004are situated. The plurality of absorbent articles 1004 are arranged inone or more stacks 1006.

The three-dimensional material may be particularly resilient tocompression so that the articles may be compressed to a certain extentin the package. It is believed that the plurality of relatively closelyspaced, relatively small, and relatively pillowy three-dimensionalprojections may act as springs to resist compression and recover once acompressive force is removed, especially in the areas in the vicinity ofthe channels. Compression recovery is important in nonwoven or othercomponent layers of absorbent articles, because such articles aretypically packaged and folded in compressed conditions. Manufacturers ofpersonal care products desire to retain most, if not all of the as-madecaliper for aesthetic and performance purposes. Furthermore, withoutbeing bound by theory, it is believed that in those embodiments in whichthe channels are substantially material-free, this may contribute to anunexpected, beneficial improvement in compression recovery as theyprovide spacing for at some of the three-dimensional projections to nestin during storage and transport in the compressed package state.

The articles of the invention may thus be packaged compressed at anIn-Bag Compression Rate of at least 10%, in particular of from 10% to50%, in particular from 20% to 40%. The “In-Bag Compression Rate” asused herein is one minus the height of a stack of 10 folded articlesmeasured while under compression within a bag (“In-Bag Stack Height”)divided by the height of a stack of 10 folded articles of the same typebefore compression, multiplied by 100; i.e. (1-In-Bag Stack Height/stackheight before compression)*100, reported as a percentage. Of course, thestack in the bag does not need to have exactly 10 articles, rather thevalue measured for the height of stack of article in the package isdivided by the number of articles in the stack and then multiplied by10. The method used to measure the In-Bag Stack Height is described infurther details in the Test Methods. The articles before compression maybe typically sampled from the production line between the folding unitand the stack packing unit. The stack height before compression ismeasured by taking 10 articles before compression and packing, andmeasuring their stack height as indicated for the In-Bag Stack Height.

Packages of the absorbent articles of the present disclosure may have anIn-Bag Stack Height of from 55 mm to 110 mm, preferably from 55 mm to 85mm Packages of the absorbent articles of the present disclosure may inparticular have an In-Bag Stack Height of less than 110 mm, less than105 mm, less than 100 mm, less than 95 mm, less than 90 mm, specificallyreciting all 0.1 mm increments within the specified ranges and allranges formed therein or thereby, according to the In-Bag Stack HeightTest described herein. For the values shared in the previous sentence,it may be desirable to have an In-Bag Stack Height of greater than 55mm, or greater than 70 mm, or greater than 75 mm, or greater than 80 mm.Alternatively, packages of the absorbent articles of the presentdisclosure may have an In-Bag Stack Height of from 70 mm to 110 mm, from75 mm to 110 mm, from 80 mm to 110 mm, from 80 mm to 105 mm, or from 80mm to 100 mm, specifically reciting all 0.1 mm increments within thespecified ranges and all ranges formed therein or thereby, according tothe In-Back Stack Height Test described herein.

Test Methods

Ball Breakthrough (BB) Test

This test determines the ball breakthrough (BB) value of an SAPcomposition. The BB value is the force (peak load, in grams force)required to rupture a layer of an SAP composition that is swollen insynthetic urine solution, under procedures specified in the test method.BB is a measure of the integrity of a layer of the SAP composition inthe swollen state.

A suitable apparatus for BB measurement is shown in FIG. 8 . Thisapparatus comprises an inner cylinder 270 which is used to contain anSAP layer 260, an outer cylinder 230, a Teflon (RTM) flat-bottomed tray240, an inner cylinder cover plate 220, and a stainless steel weight210. The inner cylinder 270 is bored from a transparent Lexan (RTM) rodor equivalent, and has an inner diameter of 6.00 cm (area=28.27 cm²),with a wall thickness of approximately 0.5 cm, and a height ofapproximately 1.50 cm. The outer-cylinder 230 is bored from a Lexan rodor equivalent, and has an inner diameter that is slightly larger thanthe outer diameter of the inner-cylinder 270, so that the inner-cylinder270 fits within the outer-cylinder 230 and slides freely. The outercylinder 230 has a wall thickness of approximately 0.5 cm, and a heightof approximately 1.00 cm. The bottom of the outside-cylinder 230 isfaced with a 400 mesh stainless steel screen 250 that is biaxiallystretched to tautness prior to attachment. The inner cylinder coverplate 220 is made of glass plate with a thickness of 0.8 cm and a weightof 500 g. The stainless steel weight 210 has a weight of 1700 g. Alsoused is a circular sheet (not shown) of filter paper (Whatman; 589/1; 90mm diameter).

A Tensile Tester with a burst test load cell (available fromIntelect-II-STD Tensile Tester, made by Thwing-Albert Instrument Co.,Pennsylvania) is used for this test. Referring to FIG. 9 , thisinstrument comprises a force sensing load cell 330 equipped with apolished stainless steel ball-shaped probe 290, a moving crosshead 320,a stationary crosshead 310, a circular lower platen 280, and an upperclamping platen 300 that is used to clamp the sample 260 pneumatically.The lower clamp platen 280 is mounted on the stationary crosshead 310.Both lower clamp platen 280 and upper clamp platen 300 have a diameterof 115 mm, a thickness of 2.9 mm, and a circular opening 18.65 mm indiameter. The polished stainless steel ball-shaped probe 290 has adiameter of 15.84 mm During the BB test procedure, the moving crosshead320 moves up, causing the probe 290 to contact and penetrate the sample260. When the probe 290 penetrates the sample 260, the test isconsidered complete, and the appropriate data are recorded.

Referring to the Sampling Apparatus depicted in FIG. 8 , a sheet offilter paper is placed into and centered within the flat-bottomed tray240. The inner cylinder 270 is inserted into the outside-cylinder 230. A1.0 g sample of SAP composition is added to the inner cylinder 270 anddispersed evenly on the 400 mesh stainless steel screen 250. Theassembled cylinders with SAP are transferred to the flat-bottomed tray240 onto the filter paper, and inner-cylinder cover plate 220 ispositioned onto inner-cylinder 270. A 30.0 mL aliquot of synthetic urinesolution is poured into the flat-bottomed tray 240. Care should be takennot to pour the synthetic urine solution into the tray slowly enoughthat it may be absorbed unevenly by the SAP. To avoid pouring tooslowly, the synthetic urine solution may, e.g., be poured using anautomatically dispensing pipette, e.g. Multipipette (RTM) Stream(available from Eppendorf, Hamburg, Germany), set to pour at a rate of30 ml/8.75 sec (3.43 ml/sec). The synthetic urine solution passesthrough the filter paper and through the stainless screen and isabsorbed by the absorbent polymer composition 260. Five minutes afterthe all of the fluid is completely absorbed from the tray by the SAP,the stainless steel weight 210 is placed onto the inner-cylinder coverplate 220. After an additional 25 minutes, stainless steel weight 210and inner cylinder cover plate 220 are removed. For the procedure to bevalid, all of the synthetic urine solution must be absorbed by theabsorbent polymer composition at this point. The assembled cylinderswith swelled SAP are removed from flat-bottomed tray 240, and upperclamping platen 300 is placed onto the inner-cylinder 270. The assembledcylinders with swelled SAP are inverted 180°, so that upper clampingplaten 300 is now on the bottom of the inner cylinder 270, and outercylinder 230 is carefully removed from the assembly of cylinders,leaving the swollen SAP layer 260 sitting on top of upper clampingplaten 300, and not leaving it on the stainless steel screen 250. Theinner-cylinder 270 with the layer of swollen absorbent polymer 260 isimmediately transferred to the Burst Tester for measurement of the BB.

Referring to the Burst Tester depicted in FIG. 9 , inner-cylinder 270with the swollen absorbent polymer layer 260 is centrally positioned onlower clamp platen 280 and is fixed pneumatically with upper clampingplaten 300. The measurement is performed using a break sensitivity of10.00 g and a test speed of 5.00 inch/minute. The measurement isinitiated and the crosshead 320 moves up until polished stainless steelball-shaped probe 290 penetrates absorbent material gel layer 260. Aftera sample burst is registered, moving crosshead 320 returns to startposition. The BB is expressed as peak load in grams force. The averageof three determinations is reported as the BB for the absorbent polymercomposition.

Absorption Against Pressure (AAP) Test

The AAP is measured according to EDANA method WSP 442.2-02. For purposesof the present disclosure, this method may also be used to measure theAAP of SAP having more than 0.1% SAP particles smaller than 45 microns,and in order to measure AAP, SAP may be extracted from an absorbent coreand then the EDANA test be performed.

Dry Absorbent Core Caliper Test

This test may be used to measure the caliper of the absorbent core(before use i.e. without fluid loading) in a standardized manner at thecrotch point C′ of the core or any other point.

Equipment: Mitutoyo manual caliper gauge with a resolution of 0.01 mm—orequivalent instrument.

Contact Foot: Flat circular foot with a diameter of 17.0 mm (±0.2 mm). Acircular weight may be applied to the foot (e.g., a weight with a slotto facilitate application around the instrument shaft) to achieve thetarget weight. The total weight of foot and added weight (includingshaft and potentially forces of a spring) is selected to provide 2.07kPa (0.30 psi) of pressure to the sample.

The caliper gauge is mounted with the lower surface of the contact footin an horizontal plane so that the lower surface of the contact footcontacts the center of the flat horizontal upper surface of a base plateapproximately 20×25 cm. The gauge is set to read zero with the contactfoot resting on the base plate.

Ruler: Calibrated metal ruler graduated in mm.

Stopwatch: Accuracy 1 second

Sample preparation: The core is conditioned at least 24 hours asindicated above.

Measurement procedure: The core is laid flat with the bottom side, i.e.the side intended to be placed towards the backsheet in the finishedarticle facing down. The point of measurement (e.g. the crotch point Ccorresponding to this point in the finished article) is carefully drawnon the top side of the core taking care not to compress or deform thecore.

The contact foot of the caliper gauge is raised and the core is placedflat on the base plate of the caliper gauge with the top side of thecore up so that when lowered, the center of the foot is on the markedmeasuring point.

The foot is gently lowered onto the article and released (ensurecalibration to “0” prior to the start of the measurement). The calipervalue is read to the nearest 0.01 mm, 10 seconds after the foot isreleased.

The procedure is repeated for each measuring point. If there is a foldat the measuring point, the measurement is done in the closest area tothis point but without any folds. Ten articles are measured in thismanner for a given product and the average caliper is calculated andreported with an accuracy of one tenth mm

Absorbent Article Caliper Test

The Absorbent Article Caliper Test can be performed as per the DryAbsorbent Core Caliper Test described above, the difference being thatthe caliper of the finished absorbent article is measured instead of thecaliper of the core. The point of measurement may be the intersection ofthe longitudinal axis (80) and transversal axis (90) of the absorbentarticle or the crotch point C of the article. If the absorbent articleswere provided folded and/or in a package, the articles to be measuredare unfolded and/or removed from the center area of the package. If thepackage contains more than 4 articles, the outer most two articles oneach side of the package are not used in the testing. If the packagecontains more than 4 but fewer than 14 articles, then more than onepackage of articles is required to complete the testing. If the packagecontains 14 or more articles, then only one package of articles isrequired to perform the testing. If the package contains 4 or fewerarticles then all articles in the package are measured and multiplepackages are required to perform the measurement. Caliper readingsshould be taken 24±1 hours after the article is removed from thepackage, unfolded and conditioned. Physical manipulation of productshould be minimal and restricted only to necessary sample preparation.

Any elastic components of the article that prevent the article frombeing laid flat under the caliper foot are cut or removed. These mayinclude leg cuffs or waistbands. Pant-type articles are opened or cutalong the side seams as necessary. Apply sufficient tension to flattenout any folds/wrinkles. Care is taken to avoid touching and/orcompressing the area of measurement.

In-Bag Stack Height Test

The In-Bag stack height of a package of absorbent articles is determinedas follows:

Equipment: A thickness tester with a flat, rigid horizontal slidingplate is used. The thickness tester is configured so that the horizontalsliding plate moves freely in a vertical direction with the horizontalsliding plate always maintained in a horizontal orientation directlyabove a flat, rigid horizontal base plate. The thickness tester includesa suitable device for measuring the gap between the horizontal slidingplate and the horizontal base plate to within ±0.5 mm. The horizontalsliding plate and the horizontal base plate are larger than the surfaceof the absorbent article package that contacts each plate, i.e. eachplate extends past the contact surface of the absorbent article packagein all directions. The horizontal sliding plate exerts a downward forceof 850±1 gram-force (8.34 N) on the absorbent article package, which maybe achieved by placing a suitable weight on the center of thenon-package-contacting top surface of the horizontal sliding plate sothat the total mass of the sliding plate plus added weight is 850±1grams.

Test Procedure: Absorbent article packages are equilibrated at 23±2° C.and 50±5% relative humidity prior to measurement. The horizontal slidingplate is raised and an absorbent article package is placed centrallyunder the horizontal sliding plate in such a way that the absorbentarticles within the package are in a horizontal orientation. Any handleor other packaging feature on the surfaces of the package that wouldcontact either of the plates is folded flat against the surface of thepackage so as to minimize their impact on the measurement. Thehorizontal sliding plate is lowered slowly until it contacts the topsurface of the package and then released. The gap between the horizontalplates is measured to within ±0.5 mm ten seconds after releasing thehorizontal sliding plate. Five identical packages (same size packagesand same absorbent articles counts) are measured and the arithmetic meanis reported as the package width. The “In-Bag Stack Height”=(packagewidth/absorbent article count per stack)×10 is calculated and reportedto within ±0.5 mm.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application and any patent application or patent to which thisapplication claims priority or benefit thereof, is hereby incorporatedherein by reference in its entirety unless expressly excluded orotherwise limited. The citation of any document is not an admission thatit is prior art with respect to any invention disclosed or claimedherein or that it alone, or in any combination with any other referenceor references, teaches, suggests or discloses any such invention.Further, to the extent that any meaning or definition of a term in thisdocument conflicts with any meaning or definition of the same term in adocument incorporated by reference, the meaning or definition assignedto that term in this document shall govern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. An absorbent article comprising a liquidpermeable topsheet, a liquid impermeable backsheet, an absorbent corebeing disposed between the topsheet and the backsheet, wherein theabsorbent core comprises: an absorbent material disposed in an absorbentdeposition area and enclosed in a core wrap; and a swelling chamberdisposed in between two external zones; wherein: the absorbent materialcomprises superabsorbent polymer; one or more permanent seals separatethe chamber from each of the two external zones; the swelling chamberconsists of absorbent material immobilized by water-responsive bonds,wherein said water-responsive bonds deteriorate upon exposure to watersuch that the absorbent material is flowable in the wet state; and thetwo external zones comprise absorbent material that is immobilized bythermoplastic adhesive, such that the absorbent material is immobilizedin the wet state.
 2. The absorbent article of claim 1 wherein theabsorbent material comprises less than 10% of cellulose fibers.
 3. Theabsorbent article of claim 1 wherein the core wrap comprises a liquidpermeable substrate layer.
 4. The absorbent article of claim 3 whereinthe liquid permeable substrate layer is selected from the groupconsisting of: a nonwoven, a woven, an apertured film, a mesh, a paper,and combinations thereof.
 5. The absorbent article of claim 3, whereinthe liquid permeable substrate layer has a basis weight from about 8 gsmto about 25 gsm.
 6. The absorbent article of claim 3, wherein the liquidpermeable substrate layer has a basis weight of about 60 gsm or more. 7.The absorbent article of claim 3, wherein the liquid permeable substratelayer is elastomeric.
 8. The absorbent article of claim 3, wherein thecore comprises from 5 g to 25 g, of superabsorbent polymer.
 9. Theabsorbent article of claim 1, wherein the superabsorbent polymer has avalue of absorption against pressure (AAP) of about 15 g/g to 45 g/g asmeasured with an Absorption Against Pressure Test Method.
 10. Theabsorbent article of claim 1, wherein the absorbent core comprises from0.5% to 20% of adhesive by weight of the core.
 11. The absorbent articleof claim 10, wherein the adhesive comprises a water soluble adhesive.12. The absorbent article of claim 1, wherein the length of theabsorbent core is from 150 mm to 500 mm.
 13. The absorbent article ofclaim 1, wherein the width of the absorbent core is from 40 mm to 150mm.